The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to deposit, etch or treat film on a substrate such as a semiconductor wafer. The substrate processing systems typically include a processing chamber, a gas distribution device such as a showerhead and a substrate support. During processing, the substrate is arranged on the substrate support. Different gas mixtures may be introduced into the processing chamber and heat or radio frequency (RF) plasma may be used during some processes to activate chemical reactions.
During substrate processing, a photoresist layer may be used to pattern an underlying layer. For example in FIG. 1, a substrate 30 may include a nitride layer 36 such as silicon nitride (SiN) or silicon carbonitride (SiCN) that is deposited on one or more underlying layers 40. A photoresist layer 34 may be deposited on the nitride layer 36 to pattern the nitride layer 36. However, nitrogen-containing groups from the nitride layer 36 may diffuse into the photoresist layer 34 and poison the photoresist layer 34.
In some processes, a thin oxide layer may be formed on the top of the nitride layer 36 to prevent diffusion of the N-containing groups into the photoresist layer 34. The thin oxide layer may be deposited by exposing the nitride layer 36 to oxidizing plasma. However, this approach usually forms the thin oxide layer by consuming nitride. Loss of nitride may not be acceptable in some processes due to more stringent material loss requirements of these processes.